How do I clean up a sugared Bike??! (Looong post)

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How do I clean up a sugared Bike??! (Looong post)

Hi guys,
My KMX 125 B5 (1992) has the following symptoms:

1:Starts and runs at tickover for 45 sec then cuts out (Feels like water ingress or fuel shortage)

2: The cut out can be prevented by full choking just as it starts to labour

3: The bike has been in storage for 5 yrs.


The bike has been taken to a local dealer who says there is about 1-2 KG(!!) of crystal sugar in the fuel tank. Most of the sugar is in clumps, no surprise as its not petroleum-soluble. The chances are that the bike was sugared just before storage, as I did not feel any probs during the last few days before storing it.

Troubleshooting; tried and results/observations:

New sparkplug: no change, oily looking, after a restart.

Carbs dismantled and cleaned using carb cleaner: Found a bit of varnish as I had only partially drained the tank and not the carbs for storage. floats sre fine. STILL NOT HELPED.

water-flushed the fuel system: No change
Paraffin-flushed the fuel system: No change
Steamcleaned tank and carbs: No change

Dismantled engine to check for bore damage or piston seal seizure: Bores are very mildly scored but otherwise in exceptional condition, piston seal perfect (Bike has only done 3K). Compression fine.

BOIL THE CARBS: to make sure any crystalisation from inside the jets are cleared - results pending.

Is there anything we could try? My DAS is a week away (3rd May) and my training is almost over and I am still having basic riding probs like road postioning and leaving indicators on for too long, these can only be ironed out by road work! I am supposed to be riding to Germany, first week of June, so failure is NOT an option due to time constraints. I AM SO PHUCKED


are you sure all the sugar is gone from out of the tank.try to run it off an alternative fuel source (bottle & pipe or something) and see if it still cuts out. And you did replace the fuel lines (which should be done after 5 yrs storage anyway)?does the bike have a vauum operated petrol tap? cos the symptoms described could also be caused by one such item not getting enough vacuum.

Hiya CDsorry can't help with the sugar prob' but I do have the ignition/seat key for those parts you had from Daz so if you email me your address I'll post it for you

Like RBZ says - EVERYTHING to do with the fuel system will need to be checked and possibly replaced.Is the inlet manifold between the carb and the Head ok?Ditto for the manifold between the Airbox and the Carb?I doubt it has a Vacuum tap - but remove the tap from the tank anyway cos the filters on the inside are most likely gummed hoses.strip the carbs down COMPLETELY and clean them - I bet the jets are still blocked. (looks like you might have checked that already - but do it again).as a last resort try some Petseal to seal up any shite still floating around in the tank.

RBZ,Tank residue did worry us, the bike still shows these symptoms when run off a diff source of fuel, bypassing everything untill the carb.The carb does not seem to have any form of vacuum control tubing, the tap on the tank is a straight forward manual affair again no vacuum input, just in and out apertures.I had no idea that the fuel lines need replacement! I have a 20 yr old CB750FA too. I will do them both.Demon, ta m8. I will send you an email direct. You frighten me man! how did you guys manage to condense a 512 lbs motorbike into a frame, tank and three cardboard boxs of parts???!!RegardsCD

Rice,The inlet manifolds appear fine, no leaks or crud. I hope the boilling is gonna help the carb jets (probably compressed air too, to make sure).Never heard of petseal. more info would be apreciated.I am so hacked off. If/when I find the lil cherub who did this, I'm gonna feed his bollox to the drive chain.Ta m8CD

HiIf you still have problems then try the people who clean out car injectors. They use solvent tanks and ultrasonic waves to clean them out, and they should be able to do the same for a carb.Oh, one other thing. Check the reed valves are OK. I had a problem once where the bike would idle fine, but bog down and die with any throttle which turned out to be reeds.All the bestKeith

CD condensing mo'cycles is an artform in it's own righton your sugar problem I've just had a little thought (it doesn't happen often) check that your carbs don't have individual filters built into them, my old GL1000 had them in the carbs as well as one in the fuel line and the finer particles of crap got thru to them, clogged them and gave me starvation problems,stranded me in Welshpool

Demon & Sean,The KMX is a v basic machine, not too many filters, single mikuni carb. filter in the tank tap was checked, I believe. The carbs have been drained ad nauseum.Rice: the manifolds are fine, there is a perish fracture on te rubber between the carb and engine, but its on the surface, not perforated thru.I've asked Chris (the tech) to try a new/SH carb. I simply DO NOT have time for finnesse. If it takes semtex, I is cool with dat! What does a choke do on the KMX125 B5? does it inject more fuel or reduce air flow?RegardsCD

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